1. Field of the Invention
This invention relates generally to loudspeaker systems, and more particularly to a loudspeaker system using plural sound radiators in a specific arrangement resulting in a wider dispersion of sound over the full range of audio frequencies.
2. Description of Related Art
The following art defines the present state of this field and each disclosure is hereby incorporated herein by reference:
Borisenko, U.S. Pat. No. 3,759,345, describes a stereophonic sound-reproducing system comprising two sound-reproducing sets separated by a base distance and each having a high-frequency section and a mid frequency section. The mid frequency section is provided with an acoustic focuser, the acoustic axis of which is so oriented towards the base line as to make the perception of the spatial sound panorama practically independent of the listener's position on a line parallel to the base line.
LeTourneau, U.S. Pat. No. 4,179,008, describes a loudspeaker assemblage that is made up of a group of cylindrical speaker housings, with a speaker mounted in each housing. A respective spacer in the form of a wedge block or angle sleeve is interposed between adjacent housings, so that housing end closures abut respective wedges. A flexible tension member passes through each speaker housing and spacer so that when the tension member is taut, the housings and spacers are clamped to make up a relatively rigid structure having a generally toroidal shape. The tension member is releasable so that the speaker housings can be rotated about a respective axis normal to the speaker axis to selectively orient the speakers. When the tension member is taut, the speakers are retained in the selected orientation.
Carlson, U.S. Pat. No. 4,923,031, describes a loudspeaker with a pair of speaker units and a manifold chamber between the speaker units for combining the sound from both speaker units. The manifold chamber is formed by walls having an exit opening and a pair of rectangular apertures, the apertures confronting each other on opposite sides of the chamber and the exit opening being disposed normal to a plane centrally between the apertures, and the apertures and exit opening having parallel axes of elongation. One of the speaker units is coupled to each of the apertures to direct sound into the manifold chamber, and the manifold chamber is provided with a wedge confronting the apertures to direct sound parallel to the central plane between the apertures toward the exit opening. In one construction, a horn is coupled to the exit opening to conduct sound from the manifold chamber. Also in that construction, each of the speaker units has a vibratile cone confronting the apertures to which it is coupled and the cone is disposed in an enclosure provided with a bass reflex port. In another construction, four speaker units with vibratile cones are coupled to four apertures in walls forming a single manifold chamber with a single exit opening. In still another construction, a compression driver is coupled to each of the apertures through a transition section of the driver.
Sohn, U.S. Pat. No. 5,388,162, describes a speaker system designed to use wider resonant sound waves by two conventional speakers which are symmetrically and oppositely disposed to face one another along a co-axis on which both axes of the cone paper vibrator of the speakers are aligned. A sponge like sound wave absorbing material with cone-shaped recesses may be disposed in between the speaker and spherical speaker case.
Beale, U.S. Pat. No. 5,781,645, describes a loudspeaker system that comprises an array of cells each including a loudspeaker driver unit. The axes of all the driver units converge at a single point in front of the array, such point normally lying between the array and the listeners. An arrangement is described for steering the sound from the system by varying the relative level of the audio frequency signals applied to the driver units.
Gaidarov et al., U.S. Pat. No. 5,857,027, describes a loudspeaker that particularly comprises two-aperture radiator containing paired in-phase counter-radiating apertures and reproducing middle frequencies. Apertures face each other, and their geometrical axis F is positioned vertically, while the distance between apertures equals to at least the radius of aperture but does not exceed the wavelength of the lowest frequency reproduced by paired apertures.
Nakamura, U.S. Pat. No. 5,590,214, describes the efficiency of a vertical array speaker device that is raised to obtain an adequate level of sound and to confine the horizontal radiation of the listening area of a surround sound system. A pair of baffle boards are mounted to a vertical array with small diameter speakers, in symmetrical opposition, the boards are attached together at their rear edges while the front edges are held open a predetermined width.
LaCarrubba, U.S. Pat. No. 6,068,080, describes an apparatus for the redistribution of acoustic energy which comprises a lens having a reflective surface defined by the surface of revolution R1 of an elliptical arc A1 rotated about a line L through an angle .alpha.1 and the surface of revolution R2 of an elliptical arc A2 rotated about the line L through an angle .alpha.2. Each elliptical arc A1 and A2 constitutes a portion of an ellipse E1 or E2 having a focal point located at a point F1 on line L, and shares an end point P which lies on the reflective surface and the line L. The angle .alpha.1 is chosen such that the surface of revolution R1 is convex with respect to an adjoining surface S1 and the angle .alpha.2 is chosen such that the surface of revolution R2 is concave with respect to the adjoining surface S1.
Rocha, U.S. Pat. No. 6,118,883, describes an improved loudspeaker system that increases low frequency directivity and minimizes directivity discontinuities during frequency transitions, includes a first low frequency transducer, a second low frequency transducer, a middle frequency transducer assembly, and a middle frequency horn assembly having a small input aperture and a large output aperture. The middle frequency transducer assembly is attached at the small aperture of the horn assembly and directs a middle frequency acoustical signal into the horn assembly. The low frequency transducers and are mounted to opposite interior surfaces, preferably the top and bottom surfaces, of the horn assembly, and direct a low frequency acoustical signal into the horn assembly. A composite acoustical signal directed out of the horn assembly from the large aperture. The distance D.sub.1, measured from the upper transducer voice coil to the lower transducer voice coil, is substantially equal to 0.9048 of the distance D.sub.2, measured from the bottom edge of the output aperture to the top edge of the output aperture. Such a relationship between D1 and D2 results in a smooth transition and a substantially continuous acoustical beam width in the composite acoustic signal within low frequency to middle frequency crossover band.
Our prior art search with abstracts described above teaches: specific loudspeaker system layouts, an arbitrary coverage angle sound integrator, a vertical array type speaker system, a stereophonic sound reproducing system, a structure and arrangement for loudspeaker assemblage, an environment for demonstrating a stereo loudspeaker system, a high output loudspeaker system, a sound innovation speaker system, a system for controlling low frequency acoustical directivity patterns and minimizing directivity discontinuities during frequency transitions, and an apparatus for the redistribution of acoustic energy. Thus, the prior art shows, that it is known to arrange loudspeakers in a particular manner to achieve improvements in sound dispersion and uniformity of various frequency ranges. However, the prior art fails to teach opposing mid-range radiators set with differing positions relative to the listener and with their radiation impinging on a central tweeter radiator so as to improve sound quality through echo, delay, and muffling of spurious echo. The present invention fulfills these needs and provides further related advantages as described in the following summary.